> curl --proxy "http://proxyuser:*****@psproxyurl.smth.tok.eu.int:8012" --ftp-pasv --proxytunnel ftp://ftpuser:ftppassword!@ftp-2-cdn.fileservers.net:21  -v
* About to connect() to proxy psproxyurl.smth.tok.eu.int port 8012 (#0)
*   Trying 123.45.678.10...
* Connected to psproxyurl.smth.tok.eu.int (123.45.678.10) port 8012 (#0)
* Establish HTTP proxy tunnel to ftp-2-cdn.fileservers.net:21
* Proxy auth using Basic with user 'proxyuser'
* Server auth using Basic with user 'ftpuser'
> CONNECT ftp-2-cdn.fileservers.net:21 HTTP/1.1
> Host: ftp-2-cdn.fileservers.net:21
> Proxy-Authorization: Basic giEbbHJ1ePrgABerHmkpms=
> User-Agent: curl/7.29.0
> Proxy-Connection: Keep-Alive
>
< HTTP/1.1 200 Connection established
<
* Proxy replied OK to CONNECT request
< 220---------- Welcome to Pure-FTPd [privsep] [TLS] ----------
< 220-You are user number 1 of 700 allowed.
< 220-Local time is now 11:18. Server port: 21.
< 220-This is a private system - No anonymous login
< 220-IPv6 connections are also welcome on this server.
< 220 You will be disconnected after 15 minutes of inactivity.
> USER ftpuser
< 331 User ftpuser OK. Password required
> PASS ftppassword
< 230-User ftpuser has group access to:  ftpgroup
< 230-This server supports FXP transfers
< 230 OK. Current restricted directory is /
> PWD
< 257 "/" is your current location
* Entry path is '/'
> EPSV
* Connect data stream passively
< 229 Entering Extended Passive Mode (|||58841|)
*   Trying 123.45.678.10...
* Connecting to ftp-2-cdn.fileservers.net (123.45.678.10) port 8012
* Establish HTTP proxy tunnel to ftp-2-cdn.fileservers.net:58841
* Proxy auth using Basic with user 'proxyuser'
* Server auth using Basic with user 'ftpuser'
* Send failure: Socket is not connected
* Failed sending CONNECT to proxy
* Failure sending ABOR command: Failed sending data to the peer
* Closing connection 0
curl: (55) Send failure: Socket is not connected